Constant-torque winding mechanism



. Nov. 17,1925

J. J. POWERS CONSTANT TORQUE WINDING MECHANISM Filed June 23, 1922 v Inventor Jesse J Powers,

. H is Attorneg Patented Nov. 17, 1925.

' UNITED TATES PATENT OFFICE.

JESSE J. POWERS, or scriENEcrADY, NEW YORK, ASSIGNOR T0 GEN RAL ELECTRIC COMPANY, A CORPORATION or NEW YO K.

CONSTANT-TORQUE WINDING MECHANISM. I

Application filed June 23, 1922. Serial No. 570,366.

To all whom it may concern: I

Be it known that I, JEssE J; Pow Rs, a citizen of the United States, residing at Schenectady, in the county of Schenecta'dy,.

State of New York, have invented'certain new and useful Improvements in Constant- Torque lVinding Mechanism, of whichthe following is a specification.

My invention relates to improvements in rewinding mechanism such, for example, as those used to reroll a continuouslymoving record sheet of a curve drawing instrument.

Ordinarily the record sheet of such an instrument is continuously fed from one roll to another roll at-a uniform rate. In such cases "the rewinding roll cannot be driven at a uniform rate because the roll is continuously increasing in diameter. It is also important that the tension maintained on the record sheet by the re winding mechanism be kept substantially uniform and of a value sufficient to keep the sheet fairly taut without tearing. It has heretofore been proposed to drive the rewinding roll through a slip clutch from the clockwork which advances the record sheet. Such arrangements are open to the objection that the variation in torque which the clock mechanism is called upon to de-- liver due to the variation in thediameter of the rewinding roll and theyvariation in" the friction of the slip clutch introduces errors in the timing function of the clock.

My invention has for its principal object to provide an inexpensive reroll mechanism driven independently of the sheet advancing motor and which maintains the tension on the record sheet correct irrespective of changes in the diameter of the rewinding roll. A further object is the pro vision of such a mechanism in which the tension may be readily and accurately adjusted to any desired value. Other advantages of my invention will appear as the description proceeds.

The features of my invention-which I- believe to be novel and patentable will be pointed out in the claims appended hereto. The principle of operation and the pre-' ferred embodiment of my invention will of a usual-type; Fig. 2 shows an exterior side view of the automatic tensioning device "of my improved reroll mechanism; and Fig. 3 shows the interior parts of the'ten- 'sioning drum shown in Figs. 1 and 2.

Referring to Fig. 1, 1 indicates the rec ord sheet of a curve drawing instrument being advanced in the direction of the arrow at a uniform rate by a clock mechanism or other constant speed motor indicated at 2. Thedriving connection between the timing device '2 and record sheet 1 comprises in the present illustration a drum 3 having equally spaced pins 4 meshing with similar spaced holes 5 in the edges of the record sheet. The usual curve drawing pen arm of a meter, not shown, is indicated at 6. I

The rewinding spool 7 is suitably mounted in bearings of the meter framework, a part of which is shown at 8. Preferably the spool '7-is removable as indicatedin Fig. 2 in order that it may be replaced by an empty spool at suitable intervals. As shown in-Fig. 2 a shortshaft "9 extends intothe end of the spool 7 whereit is provided with reduction gearing indicated in general by the numeral 1 1 is provided between the driving motor 13 and gear 12. The driving connection between gear 12 and shaft 9 is through a spiral spring 15, the outer 'end of the "spring being shown fastened to gear 12 and the inner end to shaft 9 (see Fig.

'3). The spiral spring 15-is contained within a casing 16 secured in fixed relation to 'thegear wheel 12. The outer side surface of casing 16 is provided with a pair of cams 17 concentric with respect to shaft 9. The rigid structure comprising gear wheel 12, casing 16 and cams 17 is rotatably mounted on shaft 9 but is prevented from axial movement thereon by suitable collars, one of which is shown at 18. Screwed into the outer end of sha'ft'9 is a smaller shaft 19 forming an extension of shaft 9.. Slidably mounted on shaft 9 is a sleeve 19. This sleeve is prevented from rotating with respect to shaft 9 in any suitable manner such as by a pin extending through shaft 9 and into slots 21 formed in the sleeve 19. The inner end of sleeve 19 is forked and supports a pair of rollers 22 which ride on the cam surfaces 17. The rollers 22 are held against the cam surfaces 17 in any suitable manner such as by means of the spring 23. In the illustration of Fig. 1, the spring 23 has one end secured to the framework and its outer end is forked and fits into a groove cut in the outer surface of sleeve 19 in a manner to allow sleeve 19 to rotate and at the same time urging said sleeve together with rollers toward the cam surfaces 17. The outer end of sleeve 19 is tapered down to form a stop 25 for a trigger arm 26 when said sleeve is pushed outward by the cam surfaces 17. The trigger arm 26is secured to a shaft 27 and rotates therewith. The shaft 27 is in driving connection with the main gear train 1 1 by way of a second train of gears indicated in general by the numeral 28.

The parts just described constitute a constant torque escapement for winding up the record sheet 1. The direction of rotation for the various parts to accomplish this purpose is indicated by the arrows thereon. The spring on the motor contained within casing 13 produces sufficient torque to overcome the friction of gear train 141 and wind up spring 15. When spring 15 is wound up, it will rotate shafts 9 and 9 together with spool 7 to take up any slack in the record sheet 1. The cam surfaces 17 are so positioned with respect to the cam rollers 22 that when the spring 15 is wound up, the sleeve 19 is pushed outward so that the tapered end 25 lies in the path of trigger arm 26 and prevents its rotation, thereby locking the gear trains 14 and 28. Now, as the record sheet 1 is advanced by the timing device 2, spring 15 will continue to wind it up rotating shaft 9 and sleeve 19, thereby moving the rollers 22 in a clockwise direction opposite a lower portion of the cam surfaces 17. This permits spring 23 to move sleeve 19 inward an amount sufficient to release the trigger arm 26 and gear trains 14 and 28. This permits motor 13 to again operate to wind up spring 15. The rotation of gear 12 with respect to shaft 9 in a clockwise direction to wind up spring 15 also rotates the position of the cam surfaces 17 the same amount, thereby forcing the sleeve 19 outward against the tension of spring 23 and again locking the gear trains 14: and 28. This operation is repeated over and over again always keeping a substantial constant tension on the record sheet. By making spring 15 of con .siderable length and the rewinding cycle of short duration as herein described and illustrated, the torque produced thereby may be considered to be constant.

My improved reroll mechanism permits the use of a driving motor 13 of unlimited torque and one in which a wide variation in torque produces no harmful effect so long as the torque is suflicient to overcome the friction of the gear trains and wind-up spring 15. lVhere a clock spring is used as the motor 13, it may be arranged to be automatically wound up electrically if desired. In order to prevent too severe a shock to the mechanism when arm 26 is stopped by stop 25, it is preferable to provide a fan brake 29 on shaft 27 to keep the speed of the rewinding gears fairly low. Other equivalent locking means may be substituted for the particular locking devices shown.

The tension maintained on the record sheet may be adjusted to any desired value by changing the spring 15 for another of a different j'strength or by changing the tension of spring 15. A. convenient way of adjusting the tension of spring 15 is to hold gear 12 stationary and move sleeve 19 outward until rollers 22 clearthe high points of the cam and then rotate shaft 9 together with sleeve 19 half a revolution or more in a clockwise direction to lower the tension or in a counterclockwise direction to increase the tension. A still finer adjustment may be made by bending arm 26 toward or away from stop 25 so that the cycle of operation will take place over a different portion of the cam 17 The frequency of the operating cycle may be changed by altering the slope of the cam and the gear ratio between shaft 27 and gear 12. The various gears may be nestled about the automatic tensioning device so as to require a very small space. The parts in the drawing are spread out for illustrative purposes.

While I have described my invention as a device for rewinding a record sheet, it will be obvious that its advantages are applicable for winding devices and machines in general where it becomes important to main tain a substantially uniform tension or torque between two moving parts.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now con sider to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A shaft, a spring for driving said shaft, a torque motor for winding said spring and means for starting and stopping said motor comprising a cam mechanism having its relatively movable cooperating parts moved by said motor and said shaft respectively and a locking device for said motor moved in response to the relative position of said cam parts.

2. A winding machine comprising a winding shaft, a torque motor, a wheel in driving connection with said motor rotatively mounted on said shaft, a sprial spring about said shaft having its inner end secured thereto and its outer end secured to said wheel, a cam having its relatively movable cooperating parts respectively secured to said shaft and said wheel in such a manner that the cam is operated by relative rotative movements of said shaft and wheel and means operated by said cam for starting and stopping said motor.

3. In a winding mechanism a winding shaft, a wheel rotatively mounted on said shaft, a spiral spring connected between said shaft and gear wheel, means for connected between said shaft and wheel, means for constantly urging said wheel to turn in a direction to wind up said spring, a cam surface in fixed relation with said'wheel, a cam follower in fixed rotative relation with said shaft riding on said cam surface. where'- by relative rotation between said shaft and wheel causes the operation of said cam, and means moved by said cam for locking said wheel. against rotative movement in one angular position of said shaft and wheel and for releasing said wheel in a different angular position.

5. In combination, a record sheet, a timing device for advancing said sheet at a uniform rate and a self-contained mechanism for winding up said record sheet comprising a shaft, a torque motor, a spring between said shaft and motor for driving said shaft and an escapement between said shaftand motor adapted to cause said motor to keep said spring wound to a constant tension.

6. A constant torque device comprising a shaft,:an adjustable tension spring for driving said shaft, a torque motor for winding said spring, and an escapement between said shaft and motor adapted to cause said motor to keep said-spring wound to-the tension for which it is adjusted.

In Witness whereof, I have hereunto set my hand this 21st day of June, 1922.

JESSE J. POWERS. 

